exceptions.rb

class Exceptions < Application

  # handle RecordInvalid exceptions (406)
  def record_invalid
    @errors = request.exceptions.first.errors
    rename_error_fields!
    if content_type == :html
      request.controller.send(request.params[:action])
    else
      render 
    end
  end
end

registered_templates.rb

class RegisteredTemplates < Application
  def create
    @registered_template = configuration.registered_templates.new(params[:registered_template])

    if @registered_template.save
      head(Created, :location => uri(:configuration_registered_template,
                                     :configuration_id => configuration.id,
                                     :id => @registered_template.id))
    else
      raise RecordInvalid.new(@registered_template.errors)
    end
  end
end